Blindstitch sewing-machine.



1. WHITELAW.

BLINDSTITCH SEWING MACHINE.

' APPLICATION FILED FEB. 9. |914. 1,176,415. Patented Mar. 21, 1916.

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BLINDSTITCH SEWING MACHINE.

APPLICATION FILED FEB. 9. 1914.

1,1 76,41 5. Patented Mar. 21, 1916.

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APPLICATION FILED FEB. 9,1914.

Pafnted Mar. 21, 1916.

J. WHITELAW. L|NDsT|TCH SEWING MACHINE.

APPLICATION FILED FEB. 9. |914.

Patented Mar. 21, 1916.

UNITED STATES PATENT OFFICE JAMES WHITELAW, OF ST. LOUIS, MISSOURI.

BLINDSTIT-CH SEWING-MACHINE. L

Specication of Letters Patent.

Patented Mar. 21, 1916.

Application med February 9, 1914. Serial No. 817,579.

. sewing machines, and especially to bightlooper mechanism, working in conjunction with the reciprocating needle and complemental loop-taker for the penetrant loop, and serving to overcast a bight or loop of needle thread above the stitched surface of the work, so that said overcast loop may be engaged and positioned b y the subsequently made penetrant loop, producing a stitch affording a penetrant loop and an overcast bight for every thrust of the needle. My invention provides a two part spreadinglooper for the purpose described,'the' cooperating parts of which will serve effectively to spread the overcast bight in such position as effectively to insure proper correlation of the looper-carried portion of the needle thread with the needle-carried penetrant loop of thread.

A further object of my invention is to provide adequate means to insure proper handling of the needle thread to prevent breakage thereof under the spreading action of the looper.

In the drawings wherein I have illustrated an embodiment of my invention Figure 1 is a front'elevation of the stitching head of a blind stitch sewing machine, equipped with my improved looper; showing the needle retracted and the looper in loop-taking position. Fig. 2 is a side view with parts broken away in section showing the same parts in the aforesaid position. Fig. 3 is a view similar to Fig. 2, but with the parts in the position assumed when the needle has partially completed its penetrant stroke. Fig. 4 is a front elevation showing the parts in the position shown in Fig. 3. Fig. 5 is an enlarged detail of the looper points. Fig. 6 is a section on line 6-6 of Fig. 1. Fig. 7 is a somewhat exaggerated diagram, in plan, of the paths of movement of the looper points. Fig. 8 is a similar diagram, in side elevation, of said looper-point paths. Fig. 9 is a diagrammatic view of the stitch, with the needle, hook, looper-points and bobbin conventionalized. Fig. 10 is a fragmentary perspective view of the presser` foot.

In the particular machine illustrated as embodying my invention, 10 indicates generally the head frame, vertically disposed, in which the stitch forming mechanism is located. This frame has at its bottom a suitable presser foct 11, preferably stationary, and provided with an aperture 12 through which the goeds to be blind stitched may be presented from below by suitable work handling mechanism, so that said work may be acted upon by the needle, which reciprocates above the presser foot, across the work opening.

The needle, of course, enters and emerges on the same side of the work. The work handling mechanism such as may be employed adequately to present the work to the action of the needle forms no part of my present invention, but fragmentary parts of such mechanism are illustrated at 13, 13a representing a feed member working directly across the bed of the machine to feed the goods directly away from the operator, and 13b representing a bender suitable to work through the presser foot opening 12 to present a node of goods to the needle.

The stitch forming mechanism, located above the presser foot, comprises in general the reciprocating curved needle 14, a complemental loop taker 15 for the penetrant lcops, illustrated as a second thread carrier for ccperating with the needle to form lock stitches, and suitable thread controlling devices such as take up 17, tension 18 and other parts to be described. With these primary parts is associated the bight casting looper mechanism 16, forming, particularly, the subject of the present invention.

In the particular construction shown, all of the power movable parts of the stitchforming mechanism receive their power from a transverse jack-shaft 20, which is suitably gear driven from a main shaft 21, carried by the overhanging arm 22 of the general machine frame 10.

The needle 14, in the exempliication shown, is centrally carried by a yoke-shaped or arcuate needle bar, 25, pivoted as at 26 at the extremities of its spread limbs in suitable bearings of the frame 10, one said needle-bar-limb having a lever prolongation 27 connected by a link 28 with a wrist pin 29 of a counter-weighted crank-arm 30, carried by the jack shaft 20, so that the needle is reciprocated in its curvilinear path during each revolution of the shaft 20. The path of the needle is diagonal to the direction of feed striking from the right in the machine shown, the angle illustrated being about 45 degrees, but in some of its aspects my invention does not concern the diagonal needle arrangement. Conveniently the link '28 has a lateral extension 33 which at its extremity is pivoted as at 34 to a slide block 35 sliding upon a generally upright stem 36 projecting from hub 37, pivoted as on shaft 38, and from which projects the primary takeup arm 17. The takeup arm 17 is thus given a differential rate of motion, giving it, in appropriate timed relation to the needle reciprocation, a rapid rise, a slow descent, and a considerable dwell in lowered position.

The loop taker 15, for taking and manipulating the penetrant loop of the needle thread, is shown as a rotary hook, containing a bobbin, so that the penetrant loop may be keyed by a second thread, but in some of its aspects my invention is not confined to this type of stitch form formation, as the needle thread loops might be enchained or otherwise keyed. The particular hook mechanism 15 comprises the hook 41, containing the bobbin case 46 and bobbin, mounted on shaft 42 at the rear wall of head frame 10, and driven in two to one relation to the rotation of jack shaft 2O through the intermediary of beveled gears 43, hook driving shaft 44 and spiral gears 45, of which latter the respective elements are carried by the shafts 44 and 20. The bobbin case 46 is retained against rotation by engagement of a notched front edge with the projection 47 of a transverse throat plate 48 which spans the presser foot in front of the hook. A shoulder 49 at the top of the generally stationary bobbin case is engaged by what I term the bobbin case release 50, which is a bell crank lever, pivoted as at 51, and having a lateral arm 52 normally raised by tension spring 53 into contact with a stop 54', but arranged in the path of movement of a finger 55 projecting rearwardly beyond the pivot point Q6 of one needle-bar-limb, which carries said linger. Thus when the needle is in raised position the finger 55 depresses bell crank arm 52 rocking the release lever 50 and causing it to move the bobbin casing slightly anti-clock-wise or counter to the direction of rotation of the hook. thereby to open a clearance between the bobbin-case retaining-projection 47 of the throat plate and its coacting notch in the bobbin-case-rim.

It will be understood of course that in the particular construction shown the needle,

traveling forward, enters and emerges from the same stitched side of the work, passes beneath the transverse throat plate and cooperates with the rotary hook, presenting the needle-thread penetrant-loop thereto, to be lassoed around the bobbin case after the fashion customary in air hooks.

The looper mechanism shown comprises a main looper point 60, carried by or constituting part of the main looper bar 61 and an auxiliary or spreader member 62 coperating with the main point in the presentation of the overcast bight in proper relation to the needle path. The main looper point 60 is power moved in a path which carries it above the work from a bight-taking posi` tion, on that side of the needle toward which the thread leads to the previously made stitch in the work, to a lower bight-presenting position off to the other side of the needle. In short, it traverses the needle path, diagonally, counter to the direction of feed of the work. The second or auxiliary looper point is moved, preferably as a result of the motions of the primary looper bar, in a path from substantiallv the same bighttaking position to a bight-presenting position off to the same side of the needle as its bight taking position. Thus the two looper members, starting from a loo-taking position on the same side of the needle, terminate their forwardmovements in loop-presenting positions-on opposite sides of the needle, so that between them they present the overcast loop or bight of needle thread with its central, yoke, or bend, portion transversely spread across the needle path and below said needle path.

While variations in design of the parts, and corresponding slight variations in the paths of movement thereof, may be made with a retention of the results and advantages attained by my particular construction, it is very advantageous to have the looper elements carry the bight very near to their lower-extremities, so that the spread bight may be brought down close to the work, permitting the employment of a thin presser foot and reducing the height of the node formed in the goods by the plunger coperating with the presser foot. I prefer that the secondary looper point 62 should have at its extremity a thread carrying lobe 64, projecting forwardly and laterally, while the main looper point, terminating abruptly, shall have in its lateral edge, which makes thread engagement, a thread groove 65. The paths of movement of the two looper points are preferably such that the main looper point travels fore and aft in a plane which is diagonal to the path of needle travel, receiving` in the course of its fore and aft travel, an up and down motion which carries it in an arched path from the relatively higher loop-takng position shown in Fig. 2 to the lower loop-presenting position shown in Fig. 3. The secondary looper bar, bent so as to present its lobe in front of the main-bar-point in loop-taking position, receives the same bodily movement as does the main looper point but in the course of its forward movement it is transversely vibrated with respect to the main looper point, so that when starting in bight-taking position its lobe stands nearer to the needle than the main looper point, and in front of the main looper point and after its engagement with the needle thread, it travels, carrying the thread bight, diagonally across the path of the needle travel in the direction of the position which finally is to be occupied by the main looper point, and then, before reaching loop-presenting position, it travels rather abruptly back to its own side of the needle path, carrying one portion of the bight with it to spread the same and leaving another portion of the overcast bight hanging in the thread groove 65 of the main looper point.

To attain the desired movements of the parts I mount the generally vertical main looper bar 61 in a slide block 66 which is preferably above the plane of the pivot of the needle bar, said slide block being carried by a shaft 67 pivotally mounted in a suitable portion of the frame 10, its pivotal axis being horizo-ntal and oblique to the vertical plane of travel of the needle, so that when rocked on the pivot thus provided, the looper-bar 61, in its fore and aft movement, travels in a plane diagonal to the plane of needle reciprocation. The main looper bar 61 thus constitutes a lever of the first class, slidable relative to its fulcrum. its upper end having connection with suitable mechanism for rocking it forward and backward and simultaneously raising and lowering it, sliding the bar in its slide block.

Specifically the upper end of the main looper bar 61 is pivotedto a wrist pin 70 carried bv crank 71 on a shaft 72 which parallels the pivot shaft or fulcrum for the slide block 66. This shaft 72 is suitably rocked. as by means of a pinion 73 thereon meshing with a gear segment 74 oscillating about aI shaft 75 and receiving its oscillatory motion from instrumentalities on the jack shaft 20. Somewhere in the train of motion between the main shaft and the looper bar a differential speed movement should be employed in order that the looper structure mav make its forward excursions rapidly, dwell in loop presenting position appropriately for coperation with the needle, and then make its return to loopengaging position in slower time. For this reason the gear segment 74 has an upward yoke extension 76 in which there slides a block 77 carried by a wrist 78 eccentrically mounted on a disk 79 which is carried by the jack shaft 20. The operative relation of the parts is such that the pin 78, traveling through its lower arc, so operates the segment 74 and gear 73 that the looper mechanism receives its forward movement of high speed; then as the block 77 rides up the yoke, the looper mechanism practically dwells in loop presenting position, and as the pin 78 moves through its upper arc, with longer leverage on the yoke 76 the looper is retracted from loop-presenting to loop-taking position at relatively slow speed, for proper cooperation with the needle at both extremes of looper-travel.

In its oscillating movement the crank 71 from which the main looper point is pendant, travels across its upper arc, reaching a lower position at its limit of forward throw than at its limit of rearward throw, so that at the end of their forward movement, or in loop presenting position, the looper points are in lower horizontal plane than at the end of their rearward movement. This difference in the distance of movement of the crank past dead center is taken advantage of in the particular construction of auxiliary or secondary looper bar herein illustrated.

The auxiliary looper bar 62 is pivoted to the main looper bar as at 80, on an axis which is slightly oblique to the plane of movement of the main looper bar so that its bodily movements up and down and fore and aft harmonize with those of the main looper', but so that its transverse movements are in a plane oblique to the plane of movement of the main looper bar. To give said auxiliary looper bar its independent lateral or transverse movements, the bar is provided above its pivot with a cam yoke 81 having therein a cam slot 82 engaging a roller 83 mounted on the slide block 66. The cam slot 82 has a general trend in an appropriate diagonal direction to throw the auxiliary looper point toward or across the needle path as the bottom of the slot approaches the engaged roller, and it may have such incidental curvature as will, in the course of the vertical movements of the main looper bar through its slide block, cause the auxiliary looper point to take precisely its derived lateral throw. It will be observed with respect to the particular construction shown that when the needle stands substantially fully retracted and the crank 71 is back of dead center, as shown in Figs. l and 2, the roller 83 is near the middle of the slot 8'2, the auxiliary looper point being to the right of the needle. Now as the needle advances toward the position shown in Fig. 3 and the crank 71 rises to dead center and descends forwardly, to throw the looper points rapidly to loop preseating position, the bottom portion of the cam slot S2 rides over the roller 83, until the crank 71 reaches dead center and consequently during part of its forward travel the auxiliary looper point is thrown to the left, passing across the line of needle travel. After the crank 71 passes dead center the yoke 81, carried downward by the main looper har, moves the cam slot 82 downward with respect to the roller 83, causing the auxiliary looper point to move back .to the right side of the needle, and as the downward displacement of the main looper bar is greatest at this end of the throw of crank 71, the auxiliary looper bar, in the construction shown, will he carried somewhat farther to the right of the needle in its final loop presenting position than it is in loop taking position. Also, it will be noted, the oblique position of the pivot 80, on which the secondary looper bar rocks, relative to the plane of movement of the main looper bar causes the extremity of the auxiliary looper po-int, which stands in front of the main looper point in loop-taking position, to stand abreast of the main looper point, close to the throat plate 48 when the parts are in loop-presenting position, so that a line through said two looper points is approximately at right angles to the plane of needle travel.

In the specific construction shown the paths of movement of the two looper parts will be substantially of the character diagrammatically shown in Figs. 7 and 8.

The presser foot is of course appropriately shaped to permit of the looper-presenting action of the looper points, and to this end is cut away, as at 11a and 11", at the places where the looper-points stand when in forwardmost and lowest position, and a groove 11c is made between said openings, to accommodate the spread bight.

In rsume, the looper members, with the auxiliary point leading, take the needlethread where it leads from the eye of the retracted needle to its anchorage in the previously made stitch; the two points take a bodily movement diagonal to the needle path, crossing it counter to the feed, with the secondary looper point leading and its lobe carrying the thread. Before reaching presenting position the auxiliary point travels back across the needle path traversing it in the same direction as the feed, delivering a part of the bight to the main looper point which continues its travel in the original diagonal plane. This spreads the loop, and, owing to the oblique position of pivot 80 with respect to the plane of travel of the main looper bar, the two looper points are brought substantially abreast at the end of their forward throw, but spread on opposite sides of the needle line. The bight-presenting position of the looper points throws the looper points both farther forward than the point of needle-thread anchorage in the preceding stitch, and below the line of needle passage, so that the yoke or bend of the bight lies in a groove in the presser foot. In this position the looper points dwell, and as the check spring 93 (hereafter mentioned) is acting at the time, the bight is held smoothly on the points until after the needle has passed above the bight and the return movement of the looper parts commences. The return movement of the looper points disengages them readily from the bight, which is left lying over the work, under the needle, to he keyed bythe interlock of the penetrant loop of needle thread with the bobbin thread. i

I have found that it is advantageous so to operate the thread-controlling devices that a small amount of slack in the needle thread is given off between the tension device and the needle at the time when the double-point looper is acting to spread and present the bight of needle thread. To lthis end I preferably provide an auxiliary takeup part, supplementing the main take-up arm and acting in harmony with the time of the looper mechanism, to give off the desired slack to facilitate loop-spreading. In the specific construction shown it will be apparent that the upper end of the auxiliary looper bar moves to the left at the time that the active lower end of said bar is moving to the right toward its loop-presenting position, and I therefore mount a secondary take-up eye, 90, upon said upper end thereof, to act on the needle thread between the tension and the needle. In the machine shown the thread n is run from the spool through eyelet 91, tension 18, secondary takeup 90, check-spring-stop-and-spring 93, take-up 17, to the needle 14. Therefore the slight thread-slacking action of the part 90 will be apparent. It is, in practice, adequate to prevent thread breakage of even very fragile thread, under the spreading action of the looper points.

The stitch made by a machine as above described is illustrated in Fig. 9, wherein b is the bobbin thread and n is the needle thread, the latter having the bights n overcast above the surface of the work, each extending from points of entrance of two successive penetrant loops of needle thread, partially to encompass the point of emergence of the last made one of said loops, and each said overcast bight being keyed by the interlock of the bobbin thread with the needlethread.

While I have herein described in some detail a specific embodiment of my invention for purposes of full disclosure of one practical exemplification thereof, it will be apparent to those skilled in the art that many changes in the construction and modilications in the arrangement of parts could be effected therein without departure from the spirit and scope of my invention and within the scope of the appended claims.

What I claim is 1. In a blind-stitch sewing machine, the combination of stitch forming mechanism for forming a series of keyed penetrant loops entering and emerging on the same face of the work, and means for overcasting a bight of thread across the surface of the work, comprising a' two part looper and means to move said parts similarly along a line in the general direction of the needle movement and separate them to present the bight.

2. In a blind-stitch sewing machine, the combination of stitch forming mechanism comprising a needle entering and emerging on the same side of the work, coacting means coperating therewith to form a series of keyed penetrant loops, and means, comprising a looper having two separable points movable bodily in unison and operating means therefor, for throwing bights of thread from beyond one extreme of the penetrant range of the needle to beyond the other eXtreme of such range, and spreading the bight to the action of the needle.

3. ln a blind stitch sewing machine, stitch forming mechanism comprising a needle entering and emerging on the same side of the work, co-acting means coperating therewith to form a series of keyed penetrant loops, and means for throwing bights of thread from beyond one extreme ofthe penetrant range of the needle to beyond the other extreme of such range, comprising a two part bight looper, said parts associated for coincident bodily movement, and one movable relative to the other for loop spreading movements, means for imparting bodily movement in unison to said looper parts, and means for relatively moving said looper parts to spread them at one extremity of their throw.

4. In a blind stitch sewing machine, means for forming a series of keyed penetrant lcops, a bight looper, comprising two looper points, and operating means for said looper points to impart to one thereof four way movement only and to the other thereof six way movement.

5. In a blind stitch sewing machine the combination of stitch forming mechanism for forming a series of keyed penetrant loops entering and emerging on the same face of the work, and means for overcasting bights of thread across the surface of the work comprising a main looper bar, a secondary looper bar carried by the main looper bar, means for imparting four way motion to the main looper bar, and means for imparting movement in a different directio-n from .the movements of the main looper bar, to the auxiliary looper bar,

whereby the points of the two looper bars move to engage, carry and spread the bights. e

6. In a blind stitch sewing machine, the

combination of stitch forming mechanism comprising a needle entering and emerging on the same side of the work, coacting means coperating therewith to form a series of keyed penetrant loops, and means for throwing bights of thread from beyond one extreme of the penetrant range of the needle to beyond the other extreme of such range and spreading the bights to the action of the needle, comprising a pendant looper member, means for vibrating said member in a plane diagonal to the plane of needle operation, a second looper member carried by the first,l and means for vibrating the second looper member transversely with respect to the planetof movement of the first said looper member. Y

7. In a blind stitch sewing machine, the combination of stitch forming mechanism comprising a needle entering and emerging 0n the same side of the work, coacting means cooperating therewith to form a series of keyed penetrant loops, and means for throwing bights of thread from beyond one extreme of the penetrant range of the needle to beyond the other extreme of such range and spreading the bights to the action of the needle, comprising a pendant looper member, means for'vibrating said member in a plane diagonal to the plane of needle operation, a second looper member pivotally carried by the first, and means for vibrating the second looper member transversely with respect to the plane of movement of the first said looper member, the pivotal axis of said second looper member being oblique to the plane of movement of the first said looper member.

S. In a sewing machine for blind stitching, the combination of a needle entering and emerging on the same side of' the work, coacting means coperating therewith to form a series of keyed penetrant loops, and means for throwing bights of thread from beyond one extreme of the penetrant range of the needle to beyond the other extreme of such range and spreading said bights to the action of the needle, comprising a main looper member, means for raising and lowering and vibrating fore-and-aft said main looper member, a part affording a fulcrum for said looper member wherein said member slides, a secondary looper member carried by the first for bodily movement therewith, and cooperating means on the fulcrum part and the secondary looper member for imparting to the secondary looper member vibrations transverse to the plane of movement of the main looper member incident to the movements of the latter.

9. In a blind stitch sewing machine, the

combination of a needle entering and emerging on the same side of the work, coacting means coperating therewith to form a series of keyed penetrant loops, and means for throwing bights of thread from beyond one extreme of the penetrant range of the needle to beyond the other extreme of such range and spreading the bights to the action of the needle, comprising a main looper` bar, a secondary looper bar, power applying means for moving said main looper bar in a predetermined path and means for moving the secondary looper bar in a different path incident to the movements of the main looper bar.

10. In a sewing machine, the combination with means for forming a series of keyed penetrant loops, and means for overcasting bights of thread from between successive ones of said penetrant loops, each to encompass the point of emergence of one of said penetrant loops, said means comprising a two point spreading looper, of a take-up for the overcast thread operated by the looper and carried by one of the looper-point-members.

11. In a sewing machine, the combination with means for forming a series of keyed penetrant loops, and looper means for overcasting and spreading thread bights, of a main take up working on said thread, and an auxiliary take up for slacking thread to compensate for the spreading of the bights.

12. In a blind stitch sewing machine, the combination of means for forming a series of keyed penetrant loops, and looper means for overcasting and spreading thread bights, comprising two looper members, one of said looper members provided with a thread carrying lobe, and means for moving said looper members in unison in a fore-and-aft direction and relative to each other in a transverse direction with respect to the line of needle travel and with respect to their plane of travel in unison.

13. In a blind stitch sewing machine, the combination with means comprising a reciprocating needle and complemental loop taking mechanism for forming a series of keyed penetrant loops, of a bight looper structure comprising a main looper member, n fulcrum member wherein said main looper member is slidingly mounted and having its axis oblique to the plane of needle travel, means for imparting movement to said main looper member, slided in and rocked upon said fulcrum member, a secondary looper member pivoted to said first looper member on an axis oblique to the said fulof the first looper member, and means to rock said secondary looper member upon its pivotal axis to spread the loop. A

14. In a blind stitch sewing machine, a presser Afoot having an opening, work handling mechanism including a bender arranged below said presser foot to present the work through the presser foot opening, stitch forming mechanism above said presser foot comprising a needle reciprocating above the presser foot, complemental loop taking mechanism, and bight looping mechanism for overcasting bights of needle thread above the presser foot comprising a two barred looper having its points arranged to spread to present the bights below the needle beyond the forward extreme of the penetrant range of said needle.

15. In a blind stitch sewing machine, a presser foot having an opening, work handling mechanism including a bender arranged below said presser foot to present the work through the presser foot opening, stitch forming mechanism above said presser foot comprising a needle reciprocating above the presser foot, complemental loop taking mechanism, and bi ght loopinginechanism for overcasting bights of needle thread above the presser foot comprising a two part looper havlng its parts relatively movable, transversely ofthe plane of needle reciprocation and movable in unison in a fore-and-aft direction, and means for moving said looper members from position on the same side of the needle path beyond one extreme of the penetrant range of the needle to position below and on opposite sides of the needle path beyond the other extreme of the penetrant range of the needle.

16. In a blind stitch sewing machine, stitch forming mechanism comprising a needle, a pivoted needle bar, a complemental hook, a bobbin case therefor having a stop thereon, a fixed stop co-acting therewith, a bobbin case release or throw-back, and means carried by the needle bar for actuating said bobbin case release to move the bobbin case stop back from the fixed stop.

In testimony whereof I hereunto set my hand in the presence of two witnesses.

JAMES VVHITELAW.

In the presence of J. D. RIPPEY, L. C. KINGSLAND. 

